What is partially indirect? It’s about a new way of interacting with two hands: one does direct input via a pen, and the other indirect via touch & gaze. This paper provides an in-depth study to investigate this constellation.

In order to study this technique, we compared it to a direct input variant (pen in dominant hand, touch in nondominant hand) and another indirect variant (touches are indirect and redirect to the pen’s position).

Three interaction techniques subject to study in this paper.

We analysed the performance data of the studied users from various perspectives, including eye hand coordination, parallelity, speed, etc. Most interesting result was accuracy: with both the indirect inputs, users zoomed more accurately (that is, the zooming point during zoom was closer to the final destination).

Why is that? By looking at the accuracy over time (during each gesture), we found that for direct touch, the accuracy decreases. This is because of the direct mapping: after touching down, the zoom pivot is fixed.

Instead, for the indirect techniques, users can still change their zooming pivot during the gesture. This is a unique property of indirect zooming, and may allow for more accurate zooming in future UIs. Users can, in principle, change the zoom target during gestures:

The accompanying video shows the conditions tested in the study.

Abstract

Bimanual pen and touch UIs are mainly based on the direct manipulation paradigm. Alternatively we propose partially-indirect bimanual input, where direct pen input is used with the dominant hand, and indirect-touch input with the non-dominant hand. As direct and indirect inputs do not overlap, users can interact in the same space without interference. We investigate two indirect-touch techniques combined with direct pen input: the first redirects touches to the user’s gaze position, and the second redirects touches to the pen position. In this paper, we present an empirical user study where we compare both partially-indirect techniques to direct pen and touch input in bimanual pan, zoom, and ink tasks. Our experimental results show that users are comparatively fast with the indirect techniques, but more accurate as users can dynamically change the zoom-target during indirect zoom gestures. Further our studies reveal that direct and indirect zoom gestures have distinct characteristics regarding spatial use, gestural use, and bimanual parallelism.